Re: [PATCH v6 5/6] arm64: dts: qcom: sm8450: Add opp table support to PCIe

From: Manivannan Sadhasivam <mani@kernel.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Manivannan Sadhasivam" <mani@kernel.org>,
	"Krishna chaitanya chundru" <quic_krichai@quicinc.com>,
	"Bjorn Andersson" <andersson@kernel.org>,
	"Konrad Dybcio" <konrad.dybcio@linaro.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Johan Hovold" <johan+linaro@kernel.org>,
	"Brian Masney" <bmasney@redhat.com>,
	"Georgi Djakov" <djakov@kernel.org>,
	linux-arm-msm@vger.kernel.org, vireshk@kernel.org,
	quic_vbadigan@quicinc.com, quic_skananth@quicinc.com,
	quic_nitegupt@quicinc.com, linux-pci@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 5/6] arm64: dts: qcom: sm8450: Add opp table support to PCIe
Date: Tue, 30 Jan 2024 18:46:25 +0530	[thread overview]
Message-ID: <20240130131625.GA2554@thinkpad> (raw)
In-Reply-To: <20240130095508.zgufudflizrpxqhy@vireshk-i7>

On Tue, Jan 30, 2024 at 03:25:08PM +0530, Viresh Kumar wrote:
> On 30-01-24, 15:18, Manivannan Sadhasivam wrote:
> > So you are saying that the ICC core itself should get the bw values from DT
> > instead of hardcoding in the driver? If so, I'd like to get the opinion from
> > Georgi/Bjorn.
> 
> Not really. The drivers or the ICC core doesn't need to do anything I
> guess. Since the values are coming via the OPP, we must just use it to
> hide all these details.
> 
> Why is the ICC core required to get into this here ? ICC core should
> be ready to get the information from DT (may or may not via the OPP
> core), or from driver.
> 

Agree. But what I'm saying is, right now there is no DT property in the
interconnect consumer nodes to specificy the bw requirements. This is all
hardcoded in the respective ICC consumer drivers.

But when we use OPP to control bw, the bw requirements come from DT. This is
what I see as a difference. Because, only nodes making use of OPP will specify
bw in DT and other nodes making use of just ICC will not.

Maybe I'm worrying too much about these details... But it looks like
inconsistency to me.

- Mani

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